CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 109,221	$ 113,654	$ 178,412	$ 246,730
Other comprehensive income (loss), net of tax:
Change in unrealized investment gains and losses	56,338	(63,646)	107,165	(44,083)
Benefit plan adjustments	(173)	(392)	(481)	(1,092)
Foreign currency translation adjustment	11	390	(964)	(1,624)
Other comprehensive income (loss), net of tax	56,176	(63,648)	105,720	(46,799)
Comprehensive income	$ 165,397	$ 50,006	$ 284,132	$ 199,931